development of hydromodification control methodologies for ... · 2. presentation joint effort:...

Development of Hydromodification Control Methodologies for the Central Coast

The Joint Effort: Phase 1

November, 2009

Agenda

1. Introductions2. Presentation

Joint Effort: Phase 1• Work to date (e.g., objectives, guiding principles)• Phase 1 Scope of Work• Communication and Outreach

Hydromodification control criteria and implementation tools: Phase 2

3. Discussion (not addressed in preceding topics)

Joint Effort Project Team

Project SponsorCentral Coast RWQCB

Dominic Roques, P.G.

Project Lead The Low Impact Development Center

Darla Inglis, Ph.D.

Phase 1 Scoping SupportTetra Tech, Inc.

Steve Carter, P.E.Chad Helmle, P.E.

Stillwater SciencesDerek Booth, Ph.D., P.E., P.G.

Definitions

Hydromodification – Alterations to the patterns and processes of runoff and sediment from a watershed into its receiving waters as a result of land-use changes; and that generally produce changes to the physical, chemical, and/or biological condition(s) of those receiving waters.Hydromodification control – generally focused on stormwater management approaches to address changes to the watershed processes that directly affect receiving waters (e.g., surface runoff, infiltration, erosion).The Hydromodification Control “Methodology” – As pertains to the Region 3 Joint Effort, the steps that must be conducted to determine the best stormwater management controls for new and redevelopment projects.Hydromodification control criteria – numeric stormwater management objectives applied to new and redevelopment projects.Watershed processes – as used in the Joint Effort, those processes and functions that occur at the water/land interface that affect the receiving waters (e.g., surface runoff, infiltration, evapotranspiration, erosion, sediment delivery).Performance-based stormwater management – A mode of management that has definable outcomes that can be measured.

The Joint Effort: Development of Hydromodification Controls for Development Projects

Implement and Refine

Methodology: Phase 1

ProjectScoping

•Create Watershed/Waterbody Linkages•Establish Criteria for Site-Scale BMPs

•Characterize Watersheds•Identify Key Watershed Processes

Develop Joint Effort Objectives and Guiding Principles

Develop Draft Methodologyand Corresponding Scope of Work

Methodology Implementation:

Phase2

I. Maximize infiltration

II. Protect critical areas

III. Minimize pollutants

IV.“Provide long-term watershed protection”

From the Regional Board

Project Goals and Guiding Principles

The intent of this project is to “manage stormwater” by protecting and/or reestablishing watershed processes (physical, chemical, and biological). The criteria for measuring successful management must be performance-based.Management prescriptions must be both scientifically supported and readily implemented.The products must provide both parcel-specific and watershed-scale benefits to municipalities and the Board—by supporting all watershed-based programs.

How do you restore and protect “watershed processes”?

1. Find them; recognize landscape variety


1. Find them; recognize landscape variety2. Characterize them in management-relevant terms


1. Find them; recognize landscape variety2. Characterize them in management-relevant terms3. Recognize the legacy of past conditions


1. Find them; recognize landscape variety2. Characterize them in management-relevant terms3. Recognize the legacy of past conditions4. Include biological outcomes


1. Find them; recognize landscape variety2. Characterize them in management-relevant terms3. Recognize the legacy of past conditions4. Include biological outcomes5. Work in actual (and representative) places




ProjectScoping


•Characterize Watersheds•Identify Key Watershed Processes




Phase2

As background for describing the work in Phase 1, let’s review some basic information related to watershed processes, the impacts of urbanization, and the challenges in protecting/restoring watersheds.

Watershed Processes

HydrologicGeomorphicPollutant fate and transport

Rainfall

Runoff

Evapotranspiration

Infiltration

Pollutant Fate/TransportSediment Transport

The Moving Target (how variability amongst watersheds can mean different starting points)

Starting pointReference conditionNaturally evolved receiving water conditionHealthy watershed processes

Change Due to Agricultural UseHydrologic impactsNew pollutant sources

The Influence of Human Activities

DevelopmentIncreased imperviousnessIncreased runoffDecreased infiltrationWater quality degradationChannel instabilityIncreased biological stress

The Influence of Human Activities

Watershed Functions

Man

agem

ent A

ctio

ns

Increased Development

Management ActionsBMPsChanging Behaviors

What’s the Goal?Typical Trend

Watershed Functions

TargetCould be dependent on waterbody conditionCould vary for each watershed

Man

agem

ent A

ctio

ns

Existing ConditionWill vary for each watershed

A Sliding Scale Based on Variable Conditions

What information is needed to determine the best local and regional strategies for stormwater management?

Protecting Key Watershed Processes

The Joint Effort will incorporate watershed objectives in the development of hydromodification control criteria for new and redevelopment. Phase 1 is the first step in this process.

Protecting Key Watershed Processes

Characterize watershedsRefine the methodology for the development of hydromodification control criteria

The Joint Effort: Phase 1

RainfallInfiltrationEvapotranspirationSurface runoffSediment deliverySediment transport

Phase 1: Watershed Characterization

Classifications of Waterbody Characteristics

Categories of Watershed Characteristics

Phase 1: Establishing the “Building Blocks”

Stratify the Landscape

-------------------------PRODUCTS:•Final classified landscape maps•Associated GIS layers

Analyze Conditions and

Processes

-------------------------PRODUCTS:•Report of findings

Refine Methodology to

Develop Hydromod

Control Criteria

-------------------------PRODUCTS:•Guidance document describing steps necessary to develop hydromodification control criteria

Characterize Landscape

(Watersheds and Receiving

Waters)

-------------------------PRODUCTS:•Maps•GIS layers

KEY: GIS FIELD ANALYSIS

Phase 1 Summary




ProjectScoping


•Characterize Watersheds




Phase2

Quantitative measuresCriteria for BMP sizingindicators for waterbody/watershed health

Qualitative measuresStakeholder acceptancePublic acceptanceRegulatory acceptance

Sc a

le

The Challenge of ScaleRegional Watershed Subwatershed Scale Site Scale

Phase 2 Considerations

Close Phase I Data Gaps

Establish Criteria for Site-Scale

BMPs

Create Linkage Between

Watershed and Waterbodies

KEY: GIS FIELD ANALYSIS

Establish Criteria for Key

Watershed/Subwatershed

Processes

Phase 2: Continued Methodology Implementation

-------------------------PRODUCTS:

- Site-scale tools/criteria for stormwater control- Implementation tools for users- Recommendations for watershed context (e.g., stormwater trading)

Scope of Work developmentMeetings with municipalities to obtain feedback to assist in developing and refining scope

Scope implementationTechnical characterization coordinationMilestone progress reporting, scope adaptations, etc.Water Board chaired Technical Advisory Committee with multiple stakeholder representation

Phase 1 Communication and Outreach

Discussion

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